Abstract
<jats:p>Recent phase-curve observations with JWST have highlighted the strong potential of spectroscopic phase curves to constrain exoplanet atmospheric dynamics and chemistry, motivating renewed interest in the phase-curve capabilities of Ariel. Phase curves provide constraints on atmospheric dynamics, heat redistribution, and cloud properties. Ariel will uniquely enable simultaneous observations across all instrument channels, covering wavelengths from 0.5 to 7.8 μm during long-duration observations. However, these observations are highly sensitive to long-term instrumental systematics, including gain variations and pointing drifts. Such effects may arise from changes in the detector electronic state, primarily driven by temperature fluctuations, persistence, and crosstalk effects. These effects occur on timescales comparable to the variations in planetary emission observed throughout the orbit. As a result, degeneracies between the instrumental drift model and the planetary flux model are expected and may be difficult to disentangle.This work investigates the ability to detrend these long-term drifts while preserving the underlying astrophysical signal. We use the Ariel Simulator ExoSim2 (Mugnai et al, 2025) framework to generate end-to-end simulations of Ariel phase-curve observations. A 1.5D radiative transfer model is first used to produce theoretical phase curves (Changeat et al, 2024), which are then injected into ExoSim2 to simulate the instrument and detector response. Because the in-flight behavior of instrumental gain drifts cannot be predicted precisely before launch, several parameterizations are adopted to model temporal gain variations.We evaluate how accurately the science parameters can be recovered under different gain-drift scenarios through a complete end-to-end analysis, from the simulation to the fitted light-curve model for the full wavelength range of Ariel’s spectroscopic channels. This study provides new insights into the potential of Ariel for phase-curve science. Future work will extend this analysis to a wider range of variability sources, including stellar variability. Retrieval models will also be applied to the simulated phase curves in order to estimate the uncertainties on astrophysical parameters.</jats:p>